Pulmonary excretion of H2 in calves with Cryptosporidium-induced malabsorption.

Pulmonary hydrogen gas (H2) concentrations were used to assess the malabsorption of dietary nutrients in preruminating calves inoculated with Cryptosporidium sp. Normal values were established in five control calves and seven calves (principals) were inoculated with 1.0 x 10(8) Cryptosporidium sp. oocysts. Hydrogen concentrations and wet fecal weights were measured at three stages: before Cryptosporidium sp. inoculation (stage 1), three days after the onset of diarrhea (stage 2), and after the resolution of diarrhea (stage 3). Mean end-breath and total-breath H2 concentrations in the principal calves were higher (P less than 0.025 and P less than 0.05) for stage 2, when compared to control values. Both end-breath and total-breath H2 concentrations were increased (P less than 0.001 and P less than 0.025, respectively) in the principal calves during stage 2 when compared to values obtained for stages 1 and 3. Concurrently, Cryptosporidium sp. infection was associated with increased (P = 0.06) fecal output during stage 2, only. The increased H2 concentrations and cumulative fecal output show that Cryptosporidium sp. caused malabsorption of fermentable nutrients.